Serosurveillance is an important component of any comprehensive surveillance system for vaccine preventable diseases (VPDs). It is the gold standard for measuring immunity in a population, thereby complementing traditional disease surveillance methods.

International programs

Serosurveillance programs are conducted at varying frequencies in a number of countries. In the United States, serosurveillance for VPDs has occurred on an ad hoc basis as a component of the National Health and Nutrition Examination Survey (NHANES). NHANES uses a cluster sampling methodology to assess the health and nutrition of Americans by interview and physical examination. The UK Health Protection Agency has a long-established annual serosurveillance program in England and Wales, using a convenience sampling method similar to that described below for the Australian serosurveillance program. The European Sero-Epidemiology Network (ESEN) was established in 1996 to coordinate and harmonise serological surveillance for VPDs in European countries.

National program

The Australian national serosurvey program, conducted by NCIRS, is a valuable resource for estimating vaccine coverage by population immunity, for immunisation program evaluation and to contribute to disease modelling. The program is conducted in collaboration with the Centre for Infectious Diseases & Microbiology Laboratory Services (CIDMLS), at Pathology West – ICPMR, Westmead. Laboratory liaison and collection of sera are managed by CIDMLS and antibody testing occurs at CIDMLS. This includes development and refinement of specific assays required for the serosurvey and not available in Australia. We have collaborated with ESEN on several programs to standardise serological assays for international comparison.

Serosurveys are conducted at approximately five yearly intervals, by collecting a bank of 7,000–10,000 sera from diagnostic laboratories throughout Australia that receive samples from hospitalised and ambulant persons. The sera collected are residual from specimens submitted for testing that would otherwise have been discarded. Ethics approval is obtained for each serosurvey. The convenience sampling method used in these surveys can introduce biases that are difficult to control in analysis. However, a comparative study using data from the first serosurvey and a cluster sampling method showed equivalent results for vaccine preventable diseases such as measles and hepatitis B.

In Australia, the first national serosurveys were conducted using sera collected in 1996–1998 and 1999, that is, on either side of the national Measles Control Campaign. Immunity to measles, mumps, rubella, varicella, hepatitis A, hepatitis B, hepatitis C, diphtheria, tetanus, polio and pertussis was tested.

The second serosurvey was conducted using sera collected in 2002 and immunity to measles, rubella, varicella, hepatitis B, pertussis, meningococcal C, cytomegalovirus and Helicobacter pylori was tested.

The third serosurvey was conducted using sera collected in 2007 and immunity to measles, mumps, rubella, varicella, pertussis, meningococcal C, diphtheria, tetanus and hepatitis B was tested.

In addition to routine national serosurveys, NCIRS also conducted an ad hoc serosurvey using sera collected in 2005 to measure immunity to human papillomavirus (HPV) before the introduction of the HPV vaccine on the National Immunisation Program.

We acknowledge that the National Centre for Immunisation Research & Surveillance (NCIRS) is on the land of the traditional owners the Aboriginal and Torres Strait Islander peoples, the First Australians, and recognise their culture, history, diversity and their deep connection to the land. Together, through research and partnership, we aim to move to a place of equity for all. NCIRS also acknowledges and pays respect to other Aboriginal and Torres Strait Islander nations from which our research, staff and community are drawn.

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Our website meets the criteria for credibility and content as defined by the Global Advisory Committee on Vaccine Safety.

We acknowledge that the National Centre for Immunisation Research & Surveillance (NCIRS) is on the land of the traditional owners the Aboriginal and Torres Strait Islander peoples, the First Australians, and recognise their culture, history, diversity and their deep connection to the land. Together, through research and partnership, we aim to move to a place of equity for all. NCIRS also acknowledges and pays respect to other Aboriginal and Torres Strait Islander nations from which our research, staff and community are drawn.